According to an inscription by Clarke at the front of the book, this notebook was used in 1890-1891 for research into the "prior art" in connection with litigation involving the Sawyer–Man Electric Co. and their U.S. Patent 317,676. The entries consist primarily of summaries of American and British patents. There also occasional references to Belgian, Canadian, French, Scottish, and Swedish patents. Many of these patents were entered as exhibits in the "McKeesport Case" (Consolidated Electric Light Co. v. McKeesport Light Co.) and the "Filament Case" (Edison Electric Light Co. v. United States Electric Lighting Co.).Toward the end of the book are summaries of books on electricity and articles in American, British, and French scientific journals. The label on the front cover is inscribed ""No. 1. Sawyer-Man Pat. in suit 317,676, page 73" and "Fibrous-Carbon Arch Case." Clarke's name and address are also inscribed on the label. The book contains 185 numbered pages; pages 78-81, 112–117, 129-130, 133-134, and 157 are blank or missing.